No integrating the power distribution into the vest - the cables. So power goes down your sling to your rifle to deliver power for optics, lasers, torch etc, and up a cable to your helmet for more optics, and so on. The battery lives on your belt kit I think in prototypes I've seen.
I don't think you would want a power cord going from your vest from your rifle. If it gets caught on something you either get stuck or your rifle loses power.
There is a lot of work on making a powered accessory rail for rifles though, so that everything on it would share the same battery. I thought that battery would always be on the rifle though.